Chemistry 11
Organic Chemistry Notes - Functional Groups
Definition: What is a functional group?
A functional group is a sequence of atoms within a parent molecule that
exhibits characteristic and predictable chemical behavior. A particular
functional group generally exhibits a particular type of behavior, regardless of
the nature of its parent molecule. These functional groups are molecular
structural features that allow chemists to classify compounds by their
reactivity.
There are many different types of functional groups in organic chemistry. We
will consider a subset - the functional groups which are most commonly
encountered in molecules throughout the physical world.
Commonly encountered functional groups
Alkane
Alkene
Alkynes
Arene
Halide
Alcohol
Ether
Amine
Aldehyde
Ketone
Carboxylic acid
Ester
Amide
Descriptions: what are these groups & what do they do?
Alkanes, Alkenes & Alkynes
 Covered
Arene




Consist of a six-carbon hexagonal ring structure, with alternating
single and double bonds between carbon molecules
An example of a hydrocarbon functional group
A single arene functional group is a carcinogenic molecule known as
benzene
Many well-known molecules contain this functional group, including
steroids, cholesterol, and tetrahydrocannabinol (THC), the active
chemical constituent of marijuana.
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Chemistry 11
Halide
 Consist of a carbon linked to a halogen atom (F, Cl, Br, or I)
 Alkyl halides are insoluble in water due to the absence of hydrogen
bonding (but are more polar than hydrocarbons)
 Alkyl halides are generally denser than water because of the relatively
larger size of the halide atoms
Alcohol
 Contain a hydroxyl (–OH) group
 Surprisingly, a major component of alcohols (including methanol,
ethanol, and isopropyl alcohol)
 Ethanol (CH3CH2OH) is a clear, colorless liquid with a characteristic,
pleasant odor – it is consumable in various beverages and is a component
(in diluted form) of most products sold at your friendly neighborhood
liquor store
 Methanol (CH3OH or wood alcohol) and isopropyl alcohol ((CH3)2CH2OH or
rubbing alcohol) are components of household products such as windex
and antifreeze. They share the characteristic odor of alcohol but, when
ingested, can cause dosage-dependent negative effects ranging from
permanent retinal damage to blindness to death. Isn’t it amazing the
difference one carbon group more, or less, makes?
Ether
 Consists of two carbon molecules single-bonded to a central oxygen
atom
 The molecule ether (CH3CH2)2O, which contains the ether functional
group, was used as a surgical anesthetic in the past
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Chemistry 11
Amine
 Consists of a nitrogen atom single-bonded to two hydrogen atoms and
one carbon atom
 Tend to have a fishy or ammonia-like odor
 Examples of common molecules containing this functional group include
ammonia and methadone (used in drug rehabilitation centers)
Carbonyl (includes aldehydes, ketones, carboxylic acids, esters, and amides)
ALDEHYDE
KETONE
Carboxylic acid
 A member of the carbonyl family of functional groups
 Carboxylic acids were among the first organic compounds to be
discovered
 Organic acids (contain carboxylic acids) tend to have a pungent odor
 Examples include acetic acid (vinegar ) and butyric acid (a component of
rancid butter)
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Chemistry 11
Ester
 A member of the carbonyl family of functional groups
 Molecules containing esters frequently have a fruity aroma
 Esters are a common component of natural and artificial flavors, including
oil of wintergreen (methyl salicylate), chocolate, apple, and
pineapple
Amide
 Consists of a nitrogen atom single-bonded to two hydrogen atoms and to
a carbonyl functional group (carbon double bonded to an oxygen)
 A member of the carbonyl family of functional groups

The amide functional group is involved in the peptide bond, which links
two amino acids together to form a protein
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